4L60E, 4L65E, 4L70E Sonnax Pinless Accumulator Piston Kit FWD, 1-2 & 3-4

Enjoy FREE USPS Priority Mail shipping with no additional charges.

Sonnax Pinless Accumulator Piston Kit for 4L60E, 4L65E, and 4L70E Transmissions (Forward, 1-2 & 3-4)

Symptoms:

• Premature wear of aluminum pistons at the pin bore
• Burnt bands and clutches
• Cracked pistons
• Delayed engagement
• Forward slip

Cause: The wear at the piston pin bore occurs due to repeated reciprocation or cracks in the plastic accumulator piston.

Sonnax's patented pinless design, featuring dual seals, effectively stabilizes the piston within the bore and enhances sealing performance, rendering pins unnecessary.

Correction: The Sonnax kit incorporates dual seals that stabilize and completely seal the piston within the bore.

Kit Contents:

1 - Pinless Forward Accumulator Piston Kit (Part No. 77987-01K)

• Piston
• D-Ring
• PTFE Seal
• Steel balls (2)

2 - Pinless Accumulator Piston Kit 1-2 / 3-4 (Part No. 77998-03K)

• Pinless Accumulator Piston (Aluminum)
• D-Ring Viton® (2)
• Seal PTFE (2)
• Steel Balls (4)
• Dual Seal design

Material: Aluminum

Forward Accumulator Piston (FWD): In GM 4L60-E, 4L65-E, and 4L70-E units, it's common for the plastic forward accumulator piston to wear or crack. This can lead to fluid loss, resulting in delayed engagement, slipping, burnt clutches, and bands. The Sonnax pinless forward accumulator piston kit 77987-01K eliminates these issues.

• Dual seals provide stable and complete sealing of the bore, ensuring a tight seal even after numerous cycles.
• Pinless design eliminates the possibility of pin leakage and prevents piston cocking with its added length.
• Includes steel balls for plugging the existing pin bore in the valve body.

1-2 & 3-4 Accumulator Pistons: In 4L60-series units, poor shift quality, burnt bands, or clutches are common due to accumulator piston wear. Repeated reciprocation causes wear at the piston pin bore interface. When wear becomes critical, fluid loss through the piston pin bore cannot be compensated due to insufficient pump volume. Additionally, the piston can become cocked and gall the accumulator bore due to pin bore wear or spring bottoming out. To prevent these conditions in the 1-2 or 3-4 accumulator bores, Sonnax offers the pinless accumulator piston kit 77998-03K.

• Pinless design eliminates the possibility of pin bore leakage and prevents piston cocking with its additional length.
• Dual seals stabilize and completely seal the bore, maintaining a tight seal even after numerous cycles.
• Steel balls are included to plug the existing pin bore in the case or cover.